So I did the sort of thing I have been aspiring to do. It helped a bit that conditions were amazing later on - proper grit friction style - the F6b+ was mind-warpingly hard and "warmed me up" (i.e. I had to sit down and shake a bit afterwards), and both F6c+s were really very good, the first one being perfectly balanced immaculate slab desperation. The main conclusion I can draw from this and previous experiences, so far, is that the Pedriza grade reality goes something like:

F6a = F6bF6a+ = F6b+F6b =F6cF6b+ = F6cF6c = F6cF6c+ = F6c+F7a = F7a??

Below F6c is such bollox that I might as well not try "easier" routes apart from token warm-ups as they are just as hard as the harder routes?? Too tired to draw any more conclusions for now....dunno what will happen tomorrow but I will try to keep an open beginner's mind.